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Slope Evaluation and Remediation
<br />West Elk Mine
<br />Somerset, Colorado
<br />A GROUND engineer directed the subsurface exploration, logged the test holes in the
<br />field and prepared the samples for transport to our laboratory.
<br />Relatively undisturbed samples of the subsurface materials were taken with a 2 -inch I.D.
<br />"California" -type liner sampler. The sampler was driven into the substrata with blows
<br />from a 140 -pound hammer falling 30 inches. This procedure is similar to the Standard
<br />Penetration Test described by ASTM Method D1586. Penetration resistance values
<br />(blows per distance driven, typically 12 inches), when properly evaluated, indicate the
<br />relative density or consistency of soils and bedrock.
<br />The approximate locations of the test holes are shown in Figure 1. Logs of the
<br />exploratory test holes are presented in Figure 2. Explanatory notes and a legend are
<br />provided in Figure 3.
<br />LABORATORY TESTING
<br />Samples retrieved from our test holes were examined and visually classified in the
<br />laboratory by the project engineer. Laboratory testing of soil samples obtained from the
<br />subject site included standard property tests, such as native moisture contents and dry
<br />densities, grain size analysis, and liquid and plastic limits. A direct shear test was also
<br />performed on select samples. Laboratory tests were performed in general accordance
<br />with applicable ASTM protocols.
<br />Data from the laboratory testing program are summarized on Table 1.
<br />GEOLOGY
<br />The project site is situated within the Somerset coal field located in Delta and Gunnison
<br />Counties and within the Piceance Basin' in western Colorado. The Piceance Basin is a
<br />northwest trending asymmetrical basin formed during the Laramide orogeny in the Late
<br />Cretaceous. Locally, the bedrock dips at relatively low gradients, typically to the north
<br />and northeast at about 5 degrees
<br />' Ellis, M.S., Freeman, V.L. and Donnell, J.R., 1988, Cross sections showing correlation of coal beds and
<br />coal zones in the Carbondale 30' x 60' quadrangle, west - central Colorado: U.S. Geological Survey, Coal
<br />Investigations Map C -97 -13, scale 1:100000.
<br />2 Rohrbacher, T. J., Molnia, C. L., Osmonson, L.M., Carter, M. D., Hoffman, W. K., Tabet, D. E., Schultz J.
<br />E., Scott, D.C., Teeters , D.D., Jones, G.E., Quick, J.C., Hucka, B.P., and Hanson, J.A., 2000, Coal
<br />Availability, Recoverability, and Economic Evaluations of Coal Resources in the Colorado Plateau: Colorado,
<br />New Mexico, and Utah: U.S. Geological Survey, Professional Paper 1625 -13, Chapter F.
<br />Job No. 11 -6014 GROUND Engineering Consultants, Inc. Page 3
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